Automatic changeover apparatus



May 7, 1957 E. SCHASCHL 2,791,230

AUTOMATIC CHANGEIOVER APPARATUS Filed Nov. 2, 1953 2 SheetsSheet 1 ELECTRICAL SUPPLY PROCESS IN V EN TOR.

BY EDWARD SGHASCHL ATTQ/fA/EX y 1957 E. SCHASCHL 2,791,230

AUTOMATIC CHANGEOVER APPARATUS i Filed Nov. 2, 1953 2 Sheets-Sheet 2 ELECT/PICA) SUPPLY IN VEN TOR.

BY EDWARD SCHASOHL ATTORNEY United States Patent Ofl'ice 2,791,230 P atented May 7, 1957 AUTOMATIC CHANGEOVER APPARATUS Edward Schaschl, Park Ridge, 11]., assignor to The Pure Oil Company, Chicago, 111., a corporation of Ohio Application November 2, 1953, Serial No. 389,745

3 Claims. (Cl. 137-112) The present invention relates to an apparatus for the continuous supply of gas to a process. In a more specific aspect, the present invention relates to an automatic changeover apparatus adapted to provide a continuous supply of gas from a plurality of alternate sources.

There are a number of processes in industry which require a continuous supply of gas from a source such as pressurized gas cylinders and the like arranged for alternate use. In these processes, the problem of switching from a supply cylinder when the gas supply has been depleted to a fresh cylinder creates a serious problem. Generally, there is no indication of when the gas in a supply cylinder has become depleted and reached the point at which the cylinder will be completely empty and should be removed and replaced by a full cylinder. This problem is particularly vexing in operations which require a continuous supply of gas as a stripping medium or for other purposes. Heretofore switching from an empty gas cylinder to a reserve or standby cylinder has been a manual operation and has required the presence of an operator to closely check the supply of gas present in the onstream cylinder. Even when an operator is present to change the process from the supply cylinder to a reserve cylinder, there is usually a lapse of time in which the supply of gas to the process is interrupted during the changeover.

It is, therefore, an object of the present invention to provide an improved apparatus for supplying a continuous stream of gas from a plurality of alternate sources.

Another object of the present invention is to provide an improved apparatus for automatically switching from an empty pressurized gas cylinder to a full pressurized gas cylinder.

Another and further object of the present invention i to provide an automatic changeover apparatus adapted to switch from a depleted gas supply source to a reserve gas supply source without the necessity of continuously checking the quantity of gas in the onstream supply source.

These and other objects of the present invention will be apparent from the following detailed description of the invention read in conjunction with the drawings, wherein:

Figure 1 represents the preferred piping lay-out for connecting a supply gas cylinder and a reserve gas cylinder and the electrical system whereby automatic changeover from one cylinder to another is brought about; and

Figure 2 represents a simplified electrical wiring diagram showing the preferred hookup of the electrical system.

In accordance with Figure 1, gas cylinders and 12 represent high pressure gas cylinders containing gas, such as carbon dioxide, etc., under pressure. Gas cylinder 10 is connected to line 14 through a suitable valve 16 and a pressure regulator 18 and gas cylinder 12 is connected to line 20 through valve 22 and pressure regulator 24. Line 14 branches off into lines 26 and 28 containing valves 30 and 32, respectively. Line 20 branches otf into lines 34 and 36 containing valves 38 and 40, respectively.

Lines 28 and 36 join to form common line 42 containing a oneway check valve 44. Lines 26 and 34 join to form common line 46 containing solenoid valve 48. Lines 42 and 46 then join to form common line 50, which in turn divides to form line 52, which is the supply line to the process being operated, and line 54 to a pressure responsive electrical circuit breaker 56. Pressure responsive electrical circuit breaker 56 is electrically connected to a holding relay 58. Power is supplied to holding relay 58 from a suitable electrical power source which can be turned on or off by manual circuit breaker 60. Holding relay 58 is also electrically connected to a signal light 62 and to solenoid valve 48.

In accordance with Figure 2, a primary electrical circuit is made up of manual circuit breaker 60a, circuit breaker 64 of pressure responsive electrical circuit breaker 56a, coil 66 of solenoid valve 48a, signal light 62a, and coil 68 of holding relay 58a. The primary circuit is completed by closing circuit breaker 64 of pressure responsive electrical circuit breaker 56a. Completion of the primary circuit in this manner energizes coil 66 of solenoid valve 48a, signal light 62a and coil 68 of holding relay 58a. Energization of coil 68 of holding relay 58a completes a secondary and a tertiary circuit through armature Contact 70 of holding relay 58a. The secondary circuit is composed of manual circuit breaker 60a, armature Contact 70 of holding relay 58a, signal light 62a and coil 66 of solenoid valve 48a, while the tertiary circuit is made up of manual circuit breaker 60a, armature con tact 70 of holding relay 58a and coil 68 of holding relay 58a. If the primary circuit is broken by opening circuit breaker 64 of pressure responsive electrical circuit breaker 56a, coil 68 of holding relay 58a remains energized by virtue of the current passing through the tertiary circuit. With coil 68 of holding relay 58a energized through the tertiary circuit, current will still pass through the secondary circuit thus maintaining signal light 62a and coil 66 of solenoid valve 48:: in an energized condition. Coil 68 of holding relay 58a may be deenergized by opening manual circuit breaker 60a to break the tertiary circuit. Deenergization of coil 68 of holding relay 58a in turn breaks the secondary circuit at armature contact 70 of holding relay 58a.

Referring again to Figure l, at the beginning of the operation gas cylinder 10 is employed as a supply cylinder while gas cylinder 12 is employed as a reserve cylinder. In order to supply gas from cylinder 10 to a process, valves 30 and 40 are closed while valves 32 and 38 are open. Under these circumstances, gas passes to the process through valve 32 and check valve 44 and also exerts pressure on the pressure tap of pressure responsive electrical circuit breaker 56. Solenoid valve 48 is also closed at this time. As soon as gas cylinder 10 is empty the pressure drops in line 50. Pressure responsive electrical circuit breaker 56, which has been set to operate at a predetermined minimum pressure, senses the drop in pressure and closes, thus making the circuit to holding relay 58, signal light 62, and solenoid valve 48, manual circuit breaker 60 being closed at this time. When solenoid valve 48 is energized, the valve opens and gas passes from reserve cylinder 12 through valve 38 and solenoid valve 48 to gas supply line 50. With gas being supplied from cylinder 12, the pressure on pressure responsive electrical circuit breaker 56 will open circuit breaker 56. However, holding relay 58 still supplies power to signal light 62 and solenoid valve 48. Since gas cylinder 19 is now empty, it can now be removed and replaced with a full gas cylinder which will become the reserve cylinder. Gas cylinder 10 is removed from the system by closing valves 30 and 32. With valves 30 and 32 still closed, valve 40 is opened and valve 38 is closed. Gas now being supplied is from gas cylinder 12 through valve 40 and check valve 44. Solenoid valve 48 is deenergized by breaking and making the circuit through manual circuit breaker 60. Valve 30 can now be opened and the side of the system that was formerl the reserve side becomes the onstream side and the side that was formerly the onstream side becomes the reserve side. Finally, when gas cylinder 12 is exhausted and the pressure drops, pressure responsive electrical circuit breaker 56 senses the drop in pressure and closes, thus energizing the holding relay 58, solenoid valve 48, and signal light 62. With solenoid valve 48 open, gas will go to the process from gas cylinder 10 through valve 30 and solenoid valve 48.

From the above description, it may be seen that a continuous supply of gas can be passed to a process with a minimum of manual operation and without the necessity of maintaining a constant watch on the system, Although it is preferred to maintain a signal light in the system, other electrically operated signalling means such as a buzzer may be employed. A signal light is pre ferred, inasmuch as the signal will remain energized until the change from the supply cylinder to the reserve cylinder has been completed. Pressure responsive electrical circuit breaker 56 may be any standard pressure responsive device capable of sensing a predetermined minimum pressure and completing an electrical circuit when this minimum pressure is attained A suitable device of this nature is described in United States Patent 2,080,836 issued to Sylvanus C. Shipley on May 18, 1937. Figure 1 of this patent describes in detail a pressure responsive mercury switch having a bellows type pressure sensing element.

Although the apparatus of the present invention is de scribed in connection with portable pressurized gas cylinders, it may be employed in any well known process where a continuous supply of gas is to be delivered from two or more alternate supply chambers. The apparatus of the present invention can obviously be adapted for use in supplying gas for household purposes as well as supplying a continuous stream of gas for industrial purposes.

Having described and illustrated my invention, what is claimed is:

1. In a fluid supply system having at least two sources of gas under pressure, a first fluid conduit connected to each of said sources by separate lines, a oneway check valve in said conduit, each of said lines being controlled by a manually operated valve, a second fluid conduit com nected to each of said sources, a separate line connecting each of said sources to said second conduit, each of said last two mentioned lines being controlled by a manually operated valve, a solenoid valve in said second fluid conduit adapted to normally remain in closed position, a common fluid conduit connecting the outlet ends of said first and second fluid conduits, a pressure responsive electrical circuit breaker having a pressure sensing element exposed to fluid pressure in said common iluid conduit, a relay the solenoid of which is connected to said solenoid valve and said pressure responsive elec trical circuit breaker in a manner such that said solenoid valve opens when said pressure responsive circuit breaker closes upon descrease in pressure in said common fluid conduit and remains open upon opening of said circuit breaker due to increase in pressure in said common fluid conduit, a second circuit breaker electrically connected to the solenoid of said relay means in a manner such that the relay is deenergizcd when said second circuit breaker is open, said second circuit breaker being adapted to be held in closed position by said relay when on ergized.

2. In a fluid supply system having at least two sources of gas under pressure, a first fluid passage connected to each of said sources by means of separate valve-controlled lines, a second fluid passage connected to each of said sources by means of separate valvecontrolled lines, a one-way check valve in said first fluid passage, a solenoid valve in said second iluid passage adapted to normally remain in closed position, a common fluid passage conneeting said first and said second fluid passages, a pres sure responsive electrical circuit breaker having its pres sure sensing element exposed to fluid in said common fluid passage, and an electrical system comprising said solenoid valve, said pressure responsive electrical circuit breaker, and relay means connected to form a primary circuit comprising in series said pressure responsive circuit breaker, the coil of said solenoid valve, and the coil of said relay means, a secondary circuit comprising in series the armature of said relay means and the coil of said solenoid valve and a tertiary circuit comprising in series the armature of. said relay means and the coil of said relay means,

3. A system in accordance with claim 2 containing a signal light connected into the primary and secondary circuits and a manually operated switch controlling all three circuits.

References Cited in the file of this patent UNITED STATES PATENTS 

